org.h2.mvstore.type

Interface DataType<T>

All Superinterfaces:

java.util.Comparator<T>

All Known Implementing Classes:

BasicDataType, ByteArrayDataType, LobStorageMap.BlobMeta.Type, LobStorageMap.BlobReference.Type, LongDataType, MetaType, NullValueDataType, ObjectDataType, RowDataType, SpatialDataType, StringDataType, ValueDataType, VersionedValueType

public interface DataType<T>
extends java.util.Comparator<T>

A data type.

Method Summary

Modifier and Type	Method and Description
int	binarySearch(T key, java.lang.Object storage, int size, int initialGuess) Perform binary search for the key within the storage
int	compare(T a, T b) Compare two keys.
T[]	createStorage(int size) Create storage object of array type to hold values
int	getMemory(T obj) Calculates the amount of used memory in bytes.
boolean	isMemoryEstimationAllowed() Whether memory estimation based on previously seen values is allowed/desirable
T	read(java.nio.ByteBuffer buff) Read an object.
void	read(java.nio.ByteBuffer buff, java.lang.Object storage, int len) Read a list of objects.
void	write(WriteBuffer buff, java.lang.Object storage, int len) Write a list of objects.
void	write(WriteBuffer buff, T obj) Write an object.

Methods inherited from interface java.util.Comparator

comparing, comparing, comparingDouble, comparingInt, comparingLong, equals, naturalOrder, nullsFirst, nullsLast, reversed, reverseOrder, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Method Detail

compare

int compare(T a,
            T b)

Compare two keys.

Specified by:

compare in interface java.util.Comparator<T>

Parameters:

a - the first key

b - the second key

Returns:

-1 if the first key is smaller, 1 if larger, and 0 if equal

Throws:

java.lang.UnsupportedOperationException - if the type is not orderable

binarySearch

int binarySearch(T key,
                 java.lang.Object storage,
                 int size,
                 int initialGuess)

Perform binary search for the key within the storage

Parameters:

key - to search for

storage - to search within (an array of type T)

size - number of data items in the storage

initialGuess - for key position

Returns:

index of the key , if found, - index of the insertion point, if not

getMemory

int getMemory(T obj)

Calculates the amount of used memory in bytes.

Parameters:

obj - the object

Returns:

the used memory

isMemoryEstimationAllowed

boolean isMemoryEstimationAllowed()

Whether memory estimation based on previously seen values is allowed/desirable

Returns:

true if memory estimation is allowed

write

void write(WriteBuffer buff,
           T obj)

Write an object.

Parameters:

buff - the target buffer

obj - the value

write

void write(WriteBuffer buff,
           java.lang.Object storage,
           int len)

Write a list of objects.

Parameters:

buff - the target buffer

storage - the objects

len - the number of objects to write

read

T read(java.nio.ByteBuffer buff)

Read an object.

Parameters:

buff - the source buffer

Returns:

the object

read

void read(java.nio.ByteBuffer buff,
          java.lang.Object storage,
          int len)

Read a list of objects.

Parameters:

buff - the target buffer

storage - the objects

len - the number of objects to read

createStorage

T[] createStorage(int size)

Create storage object of array type to hold values

Parameters:

size - number of values to hold

Returns:

storage object